The expanding commercial interest in the generation of small nano-scale electronic devices highlights a need for the generation of a new class of conductive molecules that are functionalized for use in nano-electronic device fabrication. However, the discovery of new conductive molecules for this is fraught with difficulty. For example, little is known about the specifics of how conductive molecules work. Additionally, it is difficult to connect conductive molecules to electrodes and even more difficult to perform conductivity measurements on single molecules. In addition to the difficulties in construction, the design of new molecules possessing useful properties is hampered by the lack of a facile method for correlating the effects of optical transitions to electronic molecular properties. Once a structure is designed, the synthesis, purification and growth of single crystals of molecules as large as these is not easily accomplished. Typically, multistep separations are required. Finally, the coupling of different aromatic and heteroaromatic building blocks is difficult to achieve because substituted structures are prone to side reactions and long reaction times.
In spite of these difficulties a number of conductive molecules have been synthesized. For example, Tours et al (U.S. Pat. No. 6,430,511 (S. J. Tour, Acc. Chem. Res., 33, 791, 2000) teaches the assembly of molecular structures consisting of phenylene/ethynylene units and the measurement of the resistance/conductivity of a self-assembled monolayer deposited on a pattern of electrodes. Very few of these structures have been demonstrated to display distinct negative differential resistance (NDR) (increased resistance with increasing driving voltage) and then only under specific conditions, mostly at low temperatures.
Additionally several groups (J. Chen, et al, Science, Vol 286, pg. 1550, 1999; E. W. Wong et al, JACS, 2000, 122, 5821-5840; have synthesized conducting molecules and measured the negative differential resistance behavior and conductivity of a monolayer of this material between two surfaces. C. P. Collier et al, (Science, vol. 285, 16 Jul. 1999) have synthesized rotaxanes and catenanes molecules, made monolayers of these molecules using Langmuir-Blogett techniques, and demonstrated resonant tunneling current flow derived from the reversible inter-conversion between two different states.
The above listed references teach the synthesis of useful compounds, however do not address the need for functionalized molecules specifically adapted for facile nano-device fabrication.
Applicants have met the stated need with the design and synthesis of novel aromatic and aromatic/heteroaromatic having specific substituents useful for the incorporating these molecules into nano-electronic devices.